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Find the magnitude of acceleration of the puck on the ramp

  1. Nov 29, 2008 #1
    1. The problem statement, all variables and given/known data
    A .20 kg hockey puck is launched up a metal ramp that is inclined at a 30.0 degree angle. The coefficients of static and kinetic friction between the hockey puck and the metal ramp are
    Ms= .40 kg and Mk=.30 kg , respectively. The puck's initial speed is 35.0 m/s. What is the magnitude of the acceleration of the puck on the ramp?

    2. Relevant equations
    F= ma

    3. The attempt at a solution
    N= Nj
    Fgrav= mg(cos 30- sin 30)
    Friction= MkN

    In the j direction the forces are:
    N= -1.94
    In the i direction the forces are:
    mgcos(30) + MkN=ma
    a= (mgcos(30)+ MkN)/ m =a

    then when I plug in all of the given numbers I get -1.4.
    I have tried this problem a bunch of times and cannot get anywhere close to the correct answer. What am I doing wrong?
  2. jcsd
  3. Nov 29, 2008 #2


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    Science Advisor
    Homework Helper
    Gold Member

    mostly you've got your mgsin30 and mgcos 30 mixed up.
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